linux-kernel - [RFC PATCH 11/41] random: convert add_timer_randomness() to queued

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Message-Id: <20200921075857.4424-12-nstange@suse.de>
Date:   Mon, 21 Sep 2020 09:58:27 +0200
From:   Nicolai Stange <nstange@...e.de>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     linux-crypto@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "Alexander E. Patrakov" <patrakov@...il.com>,
        "Ahmed S. Darwish" <darwish.07@...il.com>,
        Willy Tarreau <w@....eu>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Vito Caputo <vcaputo@...garu.com>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, Ray Strode <rstrode@...hat.com>,
        William Jon McCann <mccann@....edu>,
        zhangjs <zachary@...shancloud.com>,
        Andy Lutomirski <luto@...nel.org>,
        Florian Weimer <fweimer@...hat.com>,
        Lennart Poettering <mzxreary@...inter.de>,
        Peter Matthias <matthias.peter@....bund.de>,
        Marcelo Henrique Cerri <marcelo.cerri@...onical.com>,
        Roman Drahtmueller <draht@...altsekun.de>,
        Neil Horman <nhorman@...hat.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Julia Lawall <julia.lawall@...ia.fr>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Andy Lavr <andy.lavr@...il.com>,
        Eric Biggers <ebiggers@...nel.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Stephan Müller <smueller@...onox.de>,
        Torsten Duwe <duwe@...e.de>, Petr Tesarik <ptesarik@...e.cz>,
        Nicolai Stange <nstange@...e.de>
Subject: [RFC PATCH 11/41] random: convert add_timer_randomness() to queued_entropy API

In an effort to drop __credit_entropy_bits_fast() in favor of the new
__queue_entropy()/__dispatch_queued_entropy_fast() API, convert
add_timer_randomness() from the former to the latter.

There is no change in functionality at this point, because
__credit_entropy_bits_fast() has already been reimplemented on top of the
new API before.

Signed-off-by: Nicolai Stange <nstange@...e.de>
---
 drivers/char/random.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index b91d1fc08ac5..e8c86abde901 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1400,6 +1400,7 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
 	long delta, delta2, delta3;
 	bool reseed;
 	unsigned long flags;
+	struct queued_entropy q = { 0 };
 
 	sample.jiffies = jiffies;
 	sample.cycles = random_get_entropy();
@@ -1432,13 +1433,14 @@ static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
 
 	r = &input_pool;
 	spin_lock_irqsave(&r->lock, flags);
-	__mix_pool_bytes(r, &sample, sizeof(sample));
 	/*
 	 * delta is now minimum absolute delta.
 	 * Round down by 1 bit on general principles,
 	 * and limit entropy estimate to 12 bits.
 	 */
-	reseed = __credit_entropy_bits_fast(r, min_t(int, fls(delta>>1), 11));
+	__queue_entropy(r, &q, min_t(int, fls(delta>>1), 11) << ENTROPY_SHIFT);
+	__mix_pool_bytes(r, &sample, sizeof(sample));
+	reseed = __dispatch_queued_entropy_fast(r, &q);
 	spin_unlock_irqrestore(&r->lock, flags);
 	if (reseed)
 		crng_reseed(&primary_crng, r);
-- 
2.26.2